Posted By
Charlemagne
on 2024-01-29
17:31:05
|  A "new" question that is older than the road
Hi Everybody,
Sorry for that, but the more I think about it, the more I am confused...
Well,
1. Text screen:
0-Black
1-White
2-Red
3-Cyan
4-Purple
5-Green
6-Blue
7-Yellow
8-Orange
9-Brown
10-Yellow-green
11-Pink
12-Blue-green
13-Light blue
14-Dark blue
15-Light green
and a colour attribute-byte is FBBBCCCC
F=Flash (Blink)
BBB = Bright (0..7)
CCCC = Color (0..15)
Default
Colors: $0800...$0BE7 is $10 (0 001 0000 -> no flash, brightness is 1 and color is black)
2.: Graphic screen: ???
I was so puzzled about it as I could see the difference of colors between Yape and Plus4EMU... 
Default (after graphic)
Luminance: $1800...$1BFF is $F1
Colour: $1C00...$1FFF is $01
But it seems (see the picture above) that the low half of byte of luminance is not important at all... ...or I am a colourblind... BTW: what is the difference between brightness and luminance?
Lu=I/A
Br=(R+G+B)/3
And what do tint the color (eg. $01 at $1C00), the foreground or the background of the character and white and the most bright (luminance: $F1)???
How does Commodore Plus/4 mix colours?
áááááá, it drives me crazy!
Ok, I go to bed and sleep...
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Posted By
Csabo
on 2024-01-29
18:58:21
| Re: A "new" question that is older than the road
"Luminance" is the term the good ol' Commodore Plus/4 Users Guide uses all the way back in 1984, so we're using that as well. It does refer to brightness. In this context, it's the same thing.
The highest bit for luminance, in normal hires mode is used for flashing. (Example: $32 is red, $B2 is the exact same red, but flashing.)
In graphics mode, this bit is ignored, it means and does nothing.
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Posted By
Charlemagne
on 2024-01-30
18:06:14
| Re: A "new" question that is older than the road
Csabo: Thank you for your answer.
Yes, what you tell about (and you can see above) text mode is OK.
I have some books, too, what's more in Hungarian and sometimes I also read them: eg. "Plus/4 felhasználói kézikönyv, Novotrade 1987." says the following:
It says about text color attributes (p. 144), but not when graphic on, only mention (p. 145) that $1800-1BFF are supplementary bytes for high resolution screen, not more. In addition $1C00-1FFF is high resolution video matrix, not more.
I might not have been so clear, but my question refered to graphic screen, mainly how to imagine the luminance and color bytes when graphic on. What are their structure exactly?
If you have a closer look at the color attributes (in text mode) from $0800 you can realize that it ends after exactly 1000 bytes ($10) at $0BE7 and not at $0BFF ($00,$F7,$00, etc.). It is interesting for me, because...
...on the other hand (in graphic mode) the luminance and color part of memory is full of from $1800 to $1BFF (with $F1 ??? max luminance) and from $1C00 to $1FFF (with $01 = black?)
Well, the $0BE8-$0BFF, $1BE8-$1BFF and $1FE8-$1FFF are spare (free) bytes? ("black holes").
But let's come back to the main path, so the structures of luminance and color bytes in graphic mode?
Luminance-byte: ?LLL????
Colour-byte: CCCC????
Is it right? And bits are spare marked by question mark?
There are 40x25 (=1000) character on the screen, a luminance and a colour byte belong to a character.
I get lost.
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Posted By
Csabo
on 2024-01-30
19:12:56
| Re: A "new" question that is older than the road
This question was asked and answered in less than a week ago
Let me know if something is still unclear after that explanation.
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Posted By
Charlemagne
on 2024-01-31
09:09:35
| Re: A "new" question that is older than the road
Csabo: WoW, this is just what I need... Thank you, U R a real genius...
In short:
Luminance-byte is: IBBB IFFF
Colour-byte is: FFFF BBBB
It is no wonder that I was confused. This is a cross-logic... I hope LUMYDCTT do it right when render an image. I thought I understood this logic then... I am getting older...
BTW: It is very interesting that some people think about same thing at the same time. Or not very strange(?)
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Posted By
Csabo
on 2024-01-31
08:20:55
| Re: A "new" question that is older than the road
It's just a coincidence, but an interesting coincidence
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Posted By
Charlemagne
on 2024-01-31
15:03:36
| Re: A "new" question that is older than the road
Csabo: in the end here is the summary about this topic:
(namely [SOLVED] and this would be a good idea for Plus4World improvement: marking a thread like CodeProject or as StackOverflow by a check mark for the best solution)
So my mind is in the high luminance (=brightness), right now! Thanx to Csabo!
Well, the default values from $1800 and $1C00...:
$1800: $F1 (or it can be $71, or not? {because the most significant bit is ignored in this nibble})
$1C00: $01
means (~): COLOR0,2,7 and COLOR1,1,0
In addition when you try to save a PRG (in Plus4EMU or Yape) after an executed graphical program, you will be failed to do it because both of them save the basic program from $4000. This fact is so frustrating. Yape gives you a choice to store PRG between two memory addresses, but it can do it automatically. What's more... Plus4EMU saves PRG without extension by default.
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Posted By
Csabo
on 2024-01-31
15:35:00
| Re: A "new" question that is older than the road
you will be failed to do it because both of them save the basic program from $4000
That's the actual behaviour of the Plus/4, so it's emulated correctly. (If you change the emulators to C16 mode, this won't happen BTW.)
If a BASIC program is saved from $4001 (or any other location, for that matter), I would not call that "failed" since you can still load it with DLOAD just fine. Finally, if you want to move the program back to $1001, you simply have to issue a GRAPHIC CLR statement before saving.
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Posted By
Charlemagne
on 2024-02-01
09:57:25
| Re: A "new" question that is older than the road
Csabo: Yes you are right partly, because I had also been mentioned this some years ago and it seems Gaia read it and correct it... I am giving it a try right now... It works well. In turn Plus4EMU does not want to load back correctly a program in this way.
Ok, I understand what you say: it is actual behaviour of Plus/4, but..., and this is the matter if DLOAD does it well then why does not do it an emulator since it has not anything to do with the emulation of Plus/4 directly. In short: it is not a behaviour of an emulator... (see Yape, it's ok)
DLOAD (which needs some dependencies before using it, eg. attaching a D64 image) is complicated, but GRAPHIC CLR is a very good idea and hope not to forget to mention it while explaning a simple graphical program to 20 pupils at least, at the same time, at school...
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Posted By
Charlemagne
on 2024-02-03
18:04:08
| Re: A "new" question that is older than the road
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Posted By
Charlemagne
on 2024-02-05
17:21:23
| Re: A "new" question that is older than the road
THE FINAL EXAMINATION
1. question: "Where is screen-mode status stored?"
A.) $0081
B.) $0082
C.) $0083
D.) $0084
2. question: "What does $A0 mean as a screen-mode?"
A.) text
B.) multicolor
C.) graphic1
D.) graphic2
E.) graphic3
3. question: "What does a text colour attribute byte look like?" (from $0800)
A.) ILLLCCCC
B.) CCCCILLL
C.) ICCCLLLL
D.) LLLLICCC
(where I=ignored, L=luminance, C=colour)
4. question: "...and what about colours in graphic mode?" (high resolution)
A.) $1800 (colours): BBBBFFFF, and $1C00 (luminance): IBBBIFFF
B.) $1800 (colours): FFFFBBBB, and $1C00 (luminance): IFFFIBBB
C.) $1800 (luminance): IBBBIFFF, and $1C00 (colours): BBBBFFFF
D.) $1800 (luminance): IFFFIBBB, and $1C00 (colours): FFFFBBBB
E.) $1800 (colours): BBBBFFFF, and $1C00 (luminance): IFFFIBBB
F.) $1800 (colours): FFFFBBBB, and $1C00 (luminance): IBBBIFFF
G.) $1800 (luminance): IBBBIFFF, and $1C00 (colours): FFFFBBBB
H.) $1800 (luminance): IFFFIBBB, and $1C00 (colours): BBBBFFFF
(where I=ignored, F=foreground, B=background)
5. question: "...and in Enhanced Colour Mode(ECM)?" (from $0C00)
A.) CCCCCCBB
B.) BBCCCCCC
(where C=character code, B=background)
6. question: "...and what about background color in ECM?"
A.) 00: $FF16, 01: $FF17, 10: $FF18, 11: $FF19
B.) 00: $FF15, 01: $1800, 10: $1C00, 11: $FF16
C.) 00: $FF15, 01: $FF16, 10: $FF17, 11: $FF18
D.) 00: $FF15, 01: $$1C00, 10: $1800, 11: $FF16
7. question: "...in multicolor-mode?"
A.) 00: $FF15, 01: $FF16, 10: $FF17, 11: $FF18
B.) 00: $FF15, 01: $1800(hi)+$1C00(lo), 10: $1800(lo)+$1C00(hi), 11: $FF16
C.) 00: $FF15, 01: $1800(hi)+$1C00(hi), 10: $1800(lo)+$1C00(lo), 11: $FF16
D.) 00: $FF15, 01: $1800(lo)+$1C00(hi), 10: $1800(hi)+$1C00(lo), 11: $FF16
E.) 00: $FF15, 01: $1800(lo)+$1C00(lo), 10: $1800(hi)+$1C00(hi), 11: $FF16
8. question:
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